Gram Book 1 – This design is a nice one. It works great for material that has this shape on the “C” axis. It should be cut in a little larger size, and any color that has good light through the “C”, 1-6cts. This works very well cut in the Nigerian pink Tourmaline. Cut in refractive index 1.62 to 1.93 (83.6%) with no changes.